Communication System, Compact Base Station, and Communication Method

1. A communication system comprising: a mobile communication network; a fixed communication network connected to the mobile communication network; and a plurality of radio base stations capable of communicating with a mobile terminal by radio communication, wherein the radio base stations include: a first base station connected to the mobile communication network, the first base station being a macrocell base station; and second base stations connected to the fixed communication network through wire communication lines, the second base stations being femtocell base stations; a communication connection using a base station-to-base station logical interface is established between one of the second base stations and a neighboring base station located in a neighborhood of the one of the second base stations, the neighboring base station including the first base station and/or another one of the second base stations, wherein the base station-to-base station logical interface is a same logical interface as a base station-to-base station logical interface used by macrocell base stations to communicate with each other; and a relay apparatus connected between the mobile communication network and the fixed communication network, wherein the second base stations are connected to the mobile communication network through the fixed communication network and the relay apparatus, and wherein, when a communication connection using the base station-to-base station logical interface is established between the relay apparatus and the first base station, the relay apparatus and the second base stations use the base station-to-base station logical interface using a base station-to-upper node logical interface, between the relay apparatus and the second base stations by including a data of the base station-to-base station logical interface in a frame of the base station-to-upper node logical interface.

2. The communication system according to claim 1 , wherein each of the second base stations: makes a search for the neighboring base station; makes a request to a neighboring base station having responded to the search, for establishment of the communication connection; and establishes the communication connection with the neighboring base station having responded to the request.

3. A communication system comprising: a mobile communication network; a fixed communication network connected to the mobile communication network; a plurality of radio base stations capable of communicating with a mobile terminal by radio communication; and a management server holding location information of the radio base stations, wherein the radio base stations include: a first base station connected to the mobile communication network; and second base stations connected to the fixed communication network through wire communication lines, a communication connection using a base station-to-base station logical interface is established between one of the second base stations and a neighboring base station located in a neighborhood of the one of the second base stations, the neighboring base station including the first base station and/or another one of the second base stations, and wherein: each of the second base stations: obtains information about the neighboring base station from the management server; makes a request to the neighboring base station, about which the information is obtained from the management server, for establishment of the communication connection; and establishes the communication connection with the neighboring base station having responded to the request.

4. A communication system comprising: a mobile communication network; a fixed communication network connected to the mobile communication network; and a plurality of radio base stations capable of communicating with a mobile terminal by radio communication, wherein the radio base stations include: a first base station connected to the mobile communication network; and second base stations connected to the fixed communication network through wire communication lines, and a communication connection using a base station-to-base station logical interface is established between one of the second base stations and a neighboring base station located in a neighborhood of the one of the second base stations, the neighboring base station including the first base station and/or another one of the second base stations, wherein a base station-to-base station logical interface using a base station-to-upper node logical interface is used as the predetermined logical interface, wherein the communication system further comprises a communication management apparatus that is connected to each of the second base stations using the base station-to-upper node logical interface and collects information about the neighboring base station, and wherein each of the second base stations: obtains information about the neighboring base station from the communication management apparatus; makes a request through the communication management apparatus to the neighboring base station, about which the information is obtained from the communication management apparatus, for establishment of the communication connection; and establishes the communication connection with the neighboring base station having responded to the request.

5. A compact base station used for a communication system including a mobile communication network; a fixed communication network connected to the mobile communication network; and a plurality of radio base stations capable of communicating with a mobile terminal by radio communication, wherein the radio base stations include: a first base station connected to the mobile communication network, the first base station being a macrocell base station; and second base stations connected to the fixed communication network through wire communication lines, each of the second base stations serving as the compact base station, the second base stations being femtocell base stations; a communication connection using a base station-to-base station logical interface is established between one of the second base stations and a neighboring base station located in a neighborhood of the one of the second base stations, the neighboring base station including the first base station and/or another one of the second base stations, wherein the base station-to-base station logical interface is a same logical interface as a base station-to-base station logical interface used by macrocell base stations to communicate with each other; and a relay apparatus connected between the mobile communication network and the fixed communication network, wherein the second base stations are connected to the mobile communication network through the fixed communication network and the relay apparatus, and wherein, when a communication connection using the base station-to-base station logical interface is established between the relay apparatus and the first base station, the relay apparatus and the second base stations use the base station-to-base station logical interface using a base station-to-upper node logical interface, between the relay apparatus and the second base stations by including a data of the base station-to-base station logical interface in a frame of the base station-to-upper node logical interface.

6. A communication method for a communication system including a mobile communication network; a fixed communication network connected to the mobile communication network; and a plurality of radio base stations capable of communicating with a mobile terminal by radio communication, wherein the radio base stations include: a first base station connected to the mobile communication network, the first base station being a macrocell base station; second base stations connected to the fixed communication network through wire communication lines, the second base stations being femtocell base stations; a communication connection using a base station-to-base station logical interface is established between one of the second base stations and a neighboring base station located in a neighborhood of the one of the second base stations, the neighboring base station including the first base station and/or another one of the second base stations, wherein the base station-to-base station logical interface is a same logical interface as a base station-to-base station logical interface used by macrocell base stations to communicate with each other; and a relay apparatus connected between the mobile communication network and the fixed communication network, wherein the one of the second base stations performs communication with the neighboring base station through the communication connection, wherein the second base stations are connected to the mobile communication network through the fixed communication network and the relay apparatus, and wherein, when a communication connection using the base station-to-base station logical interface is established between the relay apparatus and the first base station, the relay apparatus and the second base stations use the base station-to-base station logical interface using a base station-to-upper node logical interface, between the relay apparatus and the second base stations by including a data of the base station-to-base station logical interface in a frame of the base station-to-upper node logical interface.

7. A communication system comprising: a plurality of radio base stations, each capable of communicating with a mobile terminal by radio communication and capable of establishing a communication connection using a predetermined logical interface with another radio base station; and a communication control apparatus capable of storing information on the plurality of radio base stations and capable of communicating with the plurality of radio base stations, wherein when the communication control apparatus recognizes a target base station being one of the radio base stations to newly establish the communication connection with another one of the radio base stations, the communication control apparatus notifies the plurality of radio base stations other than the target base station of a connection establishment instruction indicating an instruction to perform a connection establishment process for establishing the communication connection with the target base station, and after each of the radio base stations is notified of the connection establishment instruction from the communication control apparatus and thereby performs the connection establishment process, each of the radio base stations determines whether or not to maintain an establishment state of the communication connection with the target base station and if determined not to maintain the establishment state, then the radio base station disconnects the communication connection.

8. The communication system according to claim 7 , wherein the target base station is connected to a mobile communication network through a fixed communication network, and the communication control apparatus notifies all those radio base stations other than the target base station of the connection establishment instruction.

9. The communication system according to claim 7 , wherein the target base station is connected to a mobile communication network through a fixed communication network, and the communication control apparatus notifies a radio base station disposed in a neighborhood of the target base station among the radio base stations, of the connection establishment instruction.

10. The communication system according to claim 7 , wherein each of the radio base stations determines not to maintain the establishment state of the communication connection when, after the radio base station is notified of the connection establishment instruction from the communication control apparatus and thereby performs the connection establishment process, the predetermined logical interface established with the target base station has not been used for a predetermined period.

11. A communication system comprising: a plurality of radio base stations, each capable of communicating with a mobile terminal by radio communication and capable of establishing a communication connection using a predetermined logical interface with another radio base station; and a communication control apparatus capable of storing information on the plurality of radio base stations and capable of communicating with the plurality of radio base stations, wherein when the communication control apparatus recognizes a target base station being one of the radio base stations to newly establish the communication connection with another one of the radio base stations, the communication control apparatus notifies a radio base station disposed in a neighborhood of the target base station among the radio base stations, of a connection establishment instruction indicating an instruction to perform a connection establishment process for establishing the communication connection with the target base station.

12. The communication system according to claim 9 , wherein the communication control apparatus selects the radio base station to be notified of the connection establishment instruction from among the radio base stations, based on information indicating installed locations of the plurality of radio base stations including the target base station.

13. The communication system according to claim 7 , wherein at least one of information for performing, by the mobile terminal, movement operation between the radio base stations, information indicating interference received by the radio base stations, and load information of the radio base stations is transmitted and received between the radio base stations via the predetermined logical interface.

14. A communication control apparatus being capable of storing information on a plurality of radio base stations, each capable of establishing a communication connection using a predetermined logical interface with another radio base station, and being capable of communicating with the plurality of radio base stations, wherein when the communication control apparatus recognizes a target base station being one of the radio base stations to newly establish the communication connection with another one of the radio base stations, the communication control apparatus notifies the plurality of radio base stations other than the target base station of a connection establishment instruction indicating an instruction to perform a connection establishment process for establishing the communication connection with the target base station, and after each of the radio base stations performs the connection establishment process in response to the connection establishment instruction, the communication control apparatus determines whether or not to maintain an establishment state of the communication connection between each of the radio base stations and the target base station, and if determined not to maintain the establishment state, then the communication control apparatus performs control to disconnect the communication connection.

15. A communication method for a communication system including a plurality of radio base stations, each capable of communicating with a mobile terminal by radio communication and capable of establishing a communication connection using a predetermined logical interface with another radio base station; and a communication control apparatus capable of storing information on the plurality of radio base stations and capable of communicating with the plurality of radio base stations, the communication method comprising the steps of: when the communication control apparatus recognizes a target base station being one of the radio base stations to newly establish the communication connection with another one of the radio base stations, notifying the plurality of radio base stations other than the target base station of a connection establishment instruction indicating an instruction to perform a connection establishment process for establishing the communication connection with the target base station, and after each of the radio base stations is notified of the connection establishment instruction from the communication control apparatus and thereby performs the connection establishment process, determining whether or not to maintain an establishment state of the communication connection with the target base station and disconnecting the communication connection if determined not to maintain the establishment state.

16. The communication system according to claim 1 , wherein at least one of information for performing, by the mobile terminal, movement operation between the radio base stations, information indicating interference received by the radio base stations, and load information of the radio base stations is transmitted and received between the radio base stations via the base station-to-base station logical interface.